linux-kernel - Re: [PATCH 0/8] unwind, arm64: add sframe unwinder for kernel

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Message-ID: <CAPhsuW7bo4efVYb8uPkQ1v9TE95_CQ6+G3q4kVyt-8g-3JD6Cw@mail.gmail.com>
Date: Thu, 13 Feb 2025 12:46:08 -0800
From: Song Liu <song@...nel.org>
To: Puranjay Mohan <puranjay@...nel.org>
Cc: Indu Bhagat <indu.bhagat@...cle.com>, Weinan Liu <wnliu@...gle.com>, 
	Josh Poimboeuf <jpoimboe@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, 
	Peter Zijlstra <peterz@...radead.org>, Mark Rutland <mark.rutland@....com>, roman.gushchin@...ux.dev, 
	Will Deacon <will@...nel.org>, Ian Rogers <irogers@...gle.com>, linux-toolchains@...r.kernel.org, 
	linux-kernel@...r.kernel.org, live-patching@...r.kernel.org, 
	joe.lawrence@...hat.com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/8] unwind, arm64: add sframe unwinder for kernel

On Thu, Feb 13, 2025 at 12:38 AM Puranjay Mohan <puranjay@...nel.org> wrote:
[...]
>
> P.S. - The livepatch doesn't have copy_process() but only copy_signal(),
> yours had copy_process() somehow.

In my build, copy_signal is inlined to copy_process, unless I add noinline.
If I do add noinline, the issue will not reproduce.

I tried more combinations. The issue doesn't reproduce if I either
1) add noinline to copy_signal, so we are not patching the whole
   copy_process function;
or
2) Switch compiler from gcc 14.2.1 to gcc 11.5.0.

So it appears something in gcc 14.2.1 is causing live patch to fail
for copy_process().

Thanks,
Song

[...]